Burglar-alarm.



J. HOFMANN.

BURGLAR ALARM.

APPLICATION FILED JULY 23,1913.

1,090,061 Patented Mar. 10, 19%

WITNESSES INVENTOR e MQ (Jim/f fjfa/j/zai/lz UNITED STATES PATENT OFFICE.

JACOB HOFMANN, OF NEW YORK, N. Y.

BURGLAR-ALARM.

To all whom it may concern Be it known that I, JACOB HorMANN, a citizen of the United States, and a resident of the city of New York, borough of Manhattan, in, the county and State of New York, have invented a new and Improved Burglar-Alarm, of which the following is a full, clear, and exact description.

The invention relates to alarms ot' the detonating type, and its object is to provide a new and improved portable burglar alarm. arranged for convenient attachment to a door, window or other movable object and to invariably sound an alarm when the movable object is opened.

In order to accomplish the desired result use is made of a barrel having a closed upper end forming an anvil against which a detonating cap is to be exploded, the barrel being adapted to be suspended from one end of a cord having its other end clamped in place by the movable object at the time the latter is shut, so that on opening the movable object the cord is released to allow the barrel to drop. Use is also made of a screw cap removably held on the lower end of the barrel and a firing pin slidable in the said barrel and screw cap and projecting below the said screw cap, the firing pin being adapted to carry a detonating cap to be exploded against the said upper end of the barrel at the time the barrel drops and the firing pin strikes the floor.

A practical embodiment of the invention is represented in the accompanying drawings forming a part of this specification, in which similar characters of reference indicate corresponding parts in all the views.

Figure 1 is a perspective view illustrating the manner of attaching the device to a door as in practical use. Fig. 2 is a longitudinal section of the device. Fig. 3 is a cross section of the latter. Fig. 4c is a view of the detonating cap.

The barrel A of the burglar alarm is provided with a closed top B to which is secured one end of a cord 0 adapted to pass over a guide pulley D held on a door or window casing E, as plainly indicated in Fig. 1. The free end of the cord C is adapted to be clamped between the casing E and the door or window E at the time the latter is in closed position, to hold the barrel A suspended, and when the door or window E is opened the free end of the cord 0 is released to allow the barrel A to drop.

Specification of Letters Patent.

Application filed July 23, 1913.

Patented Mar. 10, 1914.

Serial No. 780,700.

011 the lower end of the barrel A is screwed a screw cap F and within the barrel A extends a firing pin G provided with an upper reduced portion G for carrying a detonating cap H in the form oi. a strip of paper, on which is mounted a charge, the charge extending on the top of the reduced portion G and the ends of the paper strip being bent down on the sides of the reduced portion G to be clamped thereto by a sliding ring I fitting over the said reduced por t'ion G. The firing pin G is provided with a reduced lower portion Gr extending through the screw cap F and forming with the firing pin an annular shoulder Gr adapted to rest on the bottom of the screw cap F to support the firing pin Gr within the barrel A and to hold the charge of the detonating cap H a distance below the under side of the top B.

hen the barrel A is released on opening the door or window E, as previously mentioned, then the barrel drops down and the reduced end G of the firing pin G finally strikes the floor and in doing so the barrel A slides down on the firing pin so as to move the top B into forcible engagement with the charge of the dctonating cap H to explode the said charge and thus sound an alarm. The upper portion of the barrel A is preferably provided with openings A for the escape of the detonation so that the latter is distinctly heard.

In order to permit of conveniently placing the detonating cap IT in position on the firing pin (it, the user of the burglar alarm unscrews the screw cap F and removes the firing pin G from the barrel A, and then the operator slides the ring I over the reduced end G and places the detonating cap II in position on the said reduced end G. after which the operator slips the ring I back over the reduced end Gr and over the sides of the paper strip of the dctonating cap H to lock the latter securely in position on the firing pin G. The latter is now replaced in the barrel A and the screw cap F is screwed in position on the lower end of the barrel A to confine the tiring pin G in the barrel A. as previously explained. When the burglar alarm is not in use the firing pin G is locked against movement in the barrel A, and for this purpose use is made of a set screw J screwing in the barrel A against the firing pin G to lock the latter temporarily in place so that the detonating cap H is not liable to be accidentally exploded. When the burglar alarm is placed in position for use the set screw J is retracted to allow free sliding movement of the barrel A relative to the firing pin G, as previously explained.

The burglar alarm shown and described is very simple and durable in construction and composed of comparatively few parts, not liable easily to get out of order.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. A portable burglar alarm, comprising a barrel provided with a closed top and an open bottom, a screw cap on the lower end of the barrel, a firing pin slidably mounted in the said barrel and having a reduced lower portion extending through the said screw cap and projecting below the said screw cap, the said reduced portion forming.

with the firing pin a shoulder adapted to rest on the said screw cap, and means held exteriorly on the side of the upper portion of the said firing pin for holding a detonating cap on the top of the said firing pin opposite the said closed top of the barrel to explode the said detonating'cap against the said top on dropping the barrel and causing the firing pin to slide up in the barrel.

2. A portable burglar alarm, comprising a barrel provided with a closed top and an open bottom, a screw cap on the lower end of the barrel, a firing pin slidably mounted in the said barrel and the said screw cap and projecting below the said screw cap, the uper ortion of the said firin in b6111 rep b a duced, and a clamping ring slidable on the upper reduced portion for removably holding a detonating cap in place, the said detonating cap having its charge on top of the firing pin and having its ends clamped against the sides of the said reduced portion by the said ring, the said firing pin having a reduced lower portion extending through the cap and forming a shoulder adapted to rest on the cap to limit the downward sliding motion of the firing pin in the said barrel.

3. A portable burglar alarm, comprising a barrel provided with a closed top and an open bottom, a screw cap on the lower end of the barrel, a firing pin slidably mounted in the said barrel and the said screw cap and projecting below the said screw cap, the upper portion of the said firing pin being reduced, a clamping ring slidable on the upper reduced portion for removably holding a detonating cap in place, the saiddetonating cap having its charge on top of the firing pin and having its ends clamped against the sides of the said reduced portion by the said ring, the said firing pin having a reduced lower portion extending through the cap and forming a shoulder adapted to rest on the cap to limit the downward sliding motion of the firing pin in the said barrel, and a normally retracted set screw screwing in the said barrel and adapted to engage the said firing pin to lock the latter temporarily against sliding movement.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JACOB HOFMANN.

Witnesses:

Tnno. G. HOSTER, PHILIP D. RoLLHAUs.

Copies of this patent may obtained for five cents each, by addressing the. Commissioner et Patents.

Washington, D. C. 

